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Southampton University start a supercomputer .

A £3.2m supercomputer, one of the most powerful in the UK, has been installed at

the University of Southampton.

The Iridis4 has 12,200 processors, each of which can perform a trillion calculations per second - a measurement referred to as a "teraflop".

The IBM machine also has a million gigabytes of disk space and 50 terabytes of memory.

Home computers generally have between 500GB and 2TB of disc space and about 4GB to 6GB of memory.

There are 1,024 gigabytes in a terabyte.

The university said the new machine would allow academics to work on more projects at faster speeds.

'Top 10'

Pro vice-chancellor Prof Philip Nelson said: "Staying ahead of the game in high performance computing [HPC] is vital to help the university stay competitive.

"Simulation and computation enabled by HPC are recognised globally as the third pillar of modern research and this investment will ensure we remain world leaders in this field."

Iridis4 will be used for a range of research, including engineering, archaeology and medicine, as well as computer science.

The world's most powerful computer is China's Tianhe-2, which can perform 33,860 trillion calculations per second.

The university said its new computer ranked among the top 10 in the UK.

The most powerful is at the Science and Technology Facilities Council in Warrington.

Others are based at the University of Edinburgh, the European Centre for Medium-Range Weather Forecasts and the United Kingdom Meteorological Office.

Jupiter icy moon Europa spouts water | NASA Science reporters

Water may be spouting from Jupiter's icy moon Europa - considered one of the best places to find alien life in the Solar System.

Images by the Hubble Space Telescope show surpluses of hydrogen and oxygen in the moon's southern hemisphere, say astronomers writing in Science journal.

If confirmed as water vapour plumes, it raises hopes that Europa's underground ocean can be accessed from its surface.

Future missions could probe these seas for signs of life.

Nasa's planetary science chief Dr James Green told that: "The presence of the water has led scientists to speculate that the Europa we know today harbours life.

"The plumes are incredibly exciting if they are there - they are bringing up material from the ocean. Perhaps there are organic molecules lying there on the surface of Europa."

The findings were reported at the American Geophysical Union (AGU) Fall Meeting in San Francisco, California.

Scientists discovered the enormous fountains in images taken by Hubble in November and December of last year, as well as older images from 1999.

Signatures of water (blue) detected by Hubble are overlayed on an image of Europa

They saw evidence of water being broken apart into hydrogen and oxygen over the south polar regions of Europa.

"They are consistent with two 200-km-high (125 mile-high) plumes of water vapour," said lead author Lorenz Roth, of Southwest Research Institute in San Antonio, Texas.

Every second, seven tonnes of material is ejected from the moon's surface.

Dr Kurt Retherford, also of the Southwest Research Institute, told the AGU meeting: "This is just an amazing amount.

"It is travelling at 700m a second... All of this gas comes out, and almost all falls back towards the surface - it doesn't escape out into space."

These plumes appear to be transient - they arise for just seven hours at a time.

They peak when Europa is at its farthest from Jupiter (the apocentre of its orbit) and vanish when it comes closest (the pericentre).

This means that tidal acceleration could be driving water spouting - by opening cracks in the surface ice, the researchers propose.

The team is not yet sure whether these fissures go all the way down to the liquid water beneath the moon's icy crust, or whether some other mechanism is bringing the vapour to the surface.

The researchers also want to investigate whether the plumes are similar to those seen on Saturn's moon Enceladus, where high-pressure vapour emissions escape from very narrow cracks on the body's surface.

"We have a lot of questions about how this works," said Dr Retherford.

"How thick is the ice crust? Are there lakes and ponds embedded within the layers of the ice? Do these cracks go down really deep, do they really touch the liquid water down below?

"We don't know all of these things."

The team said exploration for Europa should now be made a priority.

The US Space Agency has made some preliminary plans for a mission to the moon - the Europa Clipper, which could fly past the plumes.

However, budgetary constraints mean it may not happen for some time.

Dr Green said: "The Europa Clipper is a very expensive venture. It is expensive because it is designed to last for a fairly long period of time, potentially a year or a number of years in a very harsh radioactive environment.

"So consequently that is what we would call a flagship.

"And right now, the budget horizon is such that we are deferring that kind of mission later into the decade."

The next realistic opportunity to study the jets up close is therefore the European Space Agency's Juice mission.

Due to launch to the Jovian system in 2022, the satellite will make two close flybys of the ice-encrusted moon in the 2030s. With luck, its instrumentation will get close enough to directly sample the plumes.

Dr Retherford, who is also an investigator on a US instrument on Juice, cautioned that the European flybys would go close to the equator, whereas the Hubble data had only seen the plume activity at the southern pole so far: "We have probably observed only one of the largest plumes on Europa.

"There could be a lot of plumes, more like 10-50km high, and we're just not seeing them with our current data-sets. So it's not improbable that the Juice mission could be flying through some sort of plume near the equator, in which case we'd still have a chance to sniff out the composition of the gases coming off and do all sorts of other interesting studies,"

Urdu Politician Sms | Hearts of Poets

Urdu Politician Sms | Hearts of Poets

Nation are born in the hearts of poets,

they prosper and dies in the hands of politicians.

[Allama Muhammad Iqbal]

islamic sms in urdu | Tumhari Niyyat Ki Pemaish

islamic sms in urdu | Tumhari Niyyat Ki Pemaish

Tumhari niyyat ki pemaish us waqt hoti hai
Jb tum kisi aisy shakhs k sath bhlai kro
Jo tum ko kuch bhi nahi de sakta.
Hazrat ALI R.A.

islamic sms | Guroor Aur Ghaflat Ka

islamic sms | Guroor Aur Ghaflat Ka

Guroor Aur Ghaflat Ka
Nasha Sharab Se Bhi
Zyada Hota Hy. Jo Iss
Nashe Mein Mubtala Ho
Jata Hy Wo Jaldi Hosh Mein
Nahi Aata …
Hazrat Ali

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Is Dost Ny Apko Dil Se Salam Bheja Hai | dosti text messages

Hawaaon k Hath ek armaan bheja hai,
Roshni k zariye ek paigam bheja hai,
Fursat mile tu kabool kar lena
Is dost ny apko dil se Salam bheja hai.

We Have Known Each Other | friendship sms

We have known each other by chance,
Became friends by choice,
Still friends by decision,
and when we say Friends Forever,
Thats definitely a lifetime Promise

Pichlay Qisay Le Baitha | dosti sms in urdu

Neend to aaney Ko Thi Par Dil Pichlay Qisay Le Baitha

dost

Ab Khud KoBe-Waqt Sulany Main Kuch Waqt to Lagta Hai___!!!

Motivational Good Morning Sms

To realise the value of,,,

“One year” Ask one who failed in an exam..
“One month” Ask one who has not received his salary.
“One week” Ask one who is hospitalised.
“One day” Ask one who is on fasting..
“One hour” Ask one who is waiting for his beloved..
“One minute” Ask one who missed his train..
“One second” Ask one who just escape from an accident..

Every moment is a treasure..
Yesterday is history,
Tomorrow is mystery,
But Today is a gift..

Thats why its called present..
May ALLAH keep ur present happy & safe.! Good morning

Soraj Ki Pehli Kiran

Soraj ki pehli kiran
Din ka pehla pehar
Panchion ki pehli chehchahat
Dhanak ka pehla rang
Hawa ki dandi sansanahat
Subha ka pehla khomar
GOOD MORING
HAVE NICE DAY

latest good morning sms in urdu | Wahan Na Phool Khilty Hain

Wahan Na Phool Khilty Hain

Wahan n phool khilty hain,

Na hi mosam badalty hain,,,,,,,,,,,,,,

Wahan kuch bhi nhi hota,,,,,,,,

Jahan Pet tum nhi hoty,,,,,,

Have a Nice Day

new good morning sms | Khushiyon Ka Dour Bhi Kabhi

Khushiyon ka dour
Bhi Kabhi Aa Hi jaey Ga,,,,,,,,,,!
Dost
Gham BHI Toh Mil
Rahey hain,,,,,,,,,,,
Tamanna Kiey Baghair,,,,,
Subha Bakhar
,,,,Alsalm O Alyakum,,,,,,,

funny pathan sms collection | Yaara Dukan Wale

1 Pathan Apna Mobile Qabristan Men Dfna Rha Tha.

Man: Ye Kya Kr Rhe Ho?

Pathan: Yaara Dukan Wale Ne Kha He K Mobile DEAD Ho Gya Hai

pathan sms in urdu | 1 Pathan Cinema Mai Film Dekh Raha Tha

1 Pathan Cinema mai Film dekh raha tha.
.
Film mai 1 Shair dowarty howe araha tha.
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Pathan ne dekha tu dar gia, owr apni chadir kandhy pa dal kar bhaagny laga
Logo ne kaha: Khan Sahib mat daro, yai tu film hai
.
Pathan: Wo tu mujh ko bhi pata hai ke yai film hai, lekin wo tu janwar hai, usko kia pata

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1. FRIENDSHIP SMS

2. FOOL SMS

3. FUNNY SMS

4. GOOD LOCK SMS

5. GOOD MORNING SMS

6. GOOD NIGHT SMS

7. HUSBAND WIFE SMS

8. ISLAMIC SMS

9. LOVE SMS

10. RAMADAN SMS

11. STUDENT SMS

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2. URDU FUNNY SMS

3. URDU POETRY SMS

4. EID MUBARAK SMS

5. FARAZ FUNNY SMS

6. FARAZ URDU SMS

7. FOOL URDU SMS

8. FUNNY PATHAN SMS

9. GOOD MORNING SMS

10. HUSBAND WIFE URDU SMS

11. Ramzan Sms

12. URDU DOSTI SMS

13. URDU ISLAMIC SMS

14. URDU POLITCIAN SMS

15. SAD URDU SMS

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Propose a Khusra

How to Propose a khusra?

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Is main bhi intrested ho, Qasam se tum log.

Kon c makhlooq ho yar, had hogai yar

Logo ke baato ko | FOOL SMS IN URDU |

Aik Admi jhoot Bolne ki waja se kaafi mashhoor howa

Aik 80 sala Borhi Aurat ko pata chala to woh Dorti hui aayi aur Boli:

Beta tum Hi Duniya k sab se jhootay admi ho na?

ADMI Bola: Logon ki baton ko dafa karo.

main to aap ko dekh ker heran reh gaya k is umar mai Yeh HUSSAN O JAMAL

Yeh RANAI aur Yeh DILKASHI.. Borhi Aurat (sharmati hui):

Ay Allah, Log bhi kitne Zalim hain, Achay Bhalay SACHAY Insan ko JHOOTA kehte hain:-P:-D;-)

If Ever In Your Life

If ever in your life u r very sad n

feel that u have lost everything,

I will come, hold ur hand,

fool sms in urdu | Status hona chaye

Status original hona chaey

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Copied to yeh walaa b ha.

Number Choose Karen 1 Se 10

Number choose karen 1 se 10

tak aur

Main ap ko bataon ga k ap ki

personality kesi hy..

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Bal k yaar ap rehny hi do.

Ap wyse hi chawal sy lgtein hyn.

Love is When

Love is when you look into some one eyes

and see their heart

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Boss : Likhna PArhna aata hai? |URDU SARDAR SMS|SARDAR SMS IN URDU

Boss : Likhna PArhna aata hai?

Sardar : Likhna aata hai parhna nai.

Boss : apna naam likho

Sardar : %$*3@t(*^&%

Boss : Ye Kya Likha Hai?

Sardar : KAha Tha Likhna Ata hai

PArhna nai…

|funny sms in urdu|funny pathan sms in urdu|faraz sms funny|

FARAZ In Bakra Mandi | Faraz funny sms |faraz urdu sms|faraz sms|

FARAZ in Bakra Mandi:
Bakra Talaash Kar Kar K Thak Gaye Hain Faraz…
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Phir Kisi se Maloom Hua Ye to Gaaye Mandi hai.

Khushion se bhari | EID MOBARAK SMS | URDU EID SMS | URDU SMS |

khushion se bhari
phoolon se dhaki
khusbboan me basi,
rango se saji,
taroon me chupi,
supnon me dhali,
aur shabnam se dhuli
EID Mubarak 2 u & all ur family !!

Aziyat Bana Raha Tamam Umar | urdu poetry sms | urdu love sms | urdu shairy |

Aziyat Bana raha tamam umar yehi
aik sawal
Galib
Sab ka sath nibhany walay khud kyun
tanha reh jatay hain..

faraz funny sms I peotry in urdu I funny sms in urdu I URDU SMS I

Dard Itna Tha Zindagi Men

Dard Itna Tha Zindagi Men, Dharkan Sath Dene Se Ghabra Gai FARAZ,
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Band Thi Ankhein Kisi Ki Yaad Men, Mout Aai oR Dhoka Kha Gai..

Ajab Hai RASAM-E-ULFAT Ay l urdu funny sms l funny faraz sms l urdu sms l

ajab hai
RASAM-E-ULFAT ay
FARAZ
dil hamara hai magar
IKHTIAR
kisi aur ka hai…

English chalti hai na I URDU FUNNY SMS I

Ek ladka ladki ko dekhne gaya
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Ladke ne english me baat karne ki sochi Aur bola- English chalti hai na ?
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Ladki sharmate hue
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SODA saath ho to DESI bhi chalti hai

Dil ke chahat I URDU PEOTRY SMS I SHAIRY I URDU SMS

Dil ki CHokhat PE jo Ik Deep Jala Rakha hai,
Tere Lout ane Ka Imkan Saja Rakha hai,

Mohabbat usse ni hote urdu love sms, urdu poetry sms

Mohabbat Usse nhi Hoti Jo Khubsurt Ho
Khubsurat wo Hota Hai Jisse Mohabbat Ho

Hume Maloom Hai Do Dil I URDU LOVE SMS I URDU POETRY SMS I

Hume Maloom Hai Do Dil

Hume maloom hai do dil judaai sah nahi sakte,
Magar rasme-wafa ye hai ki, ye bhi kah nahi sakte,
Jara kuch der tum un sahilon ki cheekh sun bhar lo,
Jo laharon me to dube hain, magar sang bah nahi sakte…!!!

NEW AND AMAZING SPACE Technology: How to Find Dangerous Asteroids

Searching for potentially Earth-destroying asteroids today isn't easy.
They're dark, difficult to see from the surface of the planet, and there are a lot of them floating in the solar system. Scientists are now looking into new, higher-tech ways to find and track near-Earth objects, but for now, much of the hard work of asteroid tracking is done the old-fashioned way: with a telescope on a clear night.
NASA scientists, astronomers around the world and amateur observers with backyard telescopes devote their lives and free time to seeking out potentially hazardous near-Earth objects (NEOs). [Photos: Potentially Dangerous Asteroids]

"It all begins with an observer making observations," Gareth Williams, of the Minor Planet Center, the clearinghouse for asteroid and other minor-planet documentation, told SPACE.com "They can be observing known objects, or they can be searching for new objects, but even if they're searching for known objects — just to take a pretty picture or some reason — new objects can come into the field. About one in 1,000 of these new objects turn out to be an object that's moving anomalously when compared to other objects in the frame."
Hunting asteroids
Anomalous motion — when an object moves in a different way than other bodies in a frame — can signal something to a keen observer. The skywatcher then reports his or her findings to the Minor Planet Center (MPC), located in Cambridge, Mass., and officials with the MPC search the organization's database to try to find a match with known, already-tracked objects.
If the new observation doesn't match any known object, the MPC puts it onto the NEO confirmation page — a database where observers can find information about asteroids with orbits that have not been sufficiently traced.
The MPC functions as the central database for all information about NEOs. The astronomers of the MPC — run by the International Astronomical Union — collect and help verify all of the space-rock sightings that are reported.
An interconnected group of observers and sky surveys work to validate claims of near-Earth-object sightings on a daily basis. This month alone, observers have discovered 80 NEOs out of 656,546 observations.

Europe Launches New Project Space Metal 3D Printing

"We want to build the best quality metal products ever made," David Jarvis, ESA's Head of New Materials and Energy Research, said in a statement when the project was unveiled last week at the London Science Museum.
The group is focusing on making space-quality components by using lasers, electron beams and even plasma to melt metal alloys, Jarvis explained. The project also aims to explore the possibility of combining strong and lightweight, but more exotic metals, such as tungsten, niobium and platinum, though these materials are expensive.
As part of the initiative, four pilot 3D printing-factories are being established in Germany, Italy, Norway and the United Kingdom. David wants to help standardize the technique and bring it to the mainstream, connecting key players in the metallic 3D printing business to develop a supply chain.
ESA officials say innovations along the way to make 3D printers more viable for spacecraft could have benefits on Earth, leading to improvements in aircraft wings, jet engines and automotive systems.
ESA is hardly alone in its ambition to perfect metal 3D printing for the final frontier. Among several other NASA endeavors in additive manufacturing, the U.S. space agency recently completed a successful hot-fire test of the biggest 3D-printed rocket part built to date: an engine injector printed with nickel-chromium alloy powder.
There are several private and university-led efforts, too. Earlier this month, a group of students at the University of California, San Diego performed their first test of a 3D-printed engine made from cobalt chromium.

Introduction to Computers and Information Technology

A computer is a general purpose device that can be programmed to carry out a set of arithmetic or logical operations. Since a sequence of operations can be readily changed, the computer can solve more than one kind of problem.
Conventionally, a computer consists of at least one processing element, typically a central processing unit (CPU) and some form of memory. The processing element carries out arithmetic and logic operations, and a sequencing and control unit that can change the order of operations based on stored information. Peripheral devices allow information to be retrieved from an external source, and the result of operations saved and retrieved.
The first electronic digital computers were developed between 1940 and 1945. Originally they were the size of a large room, consuming as much power as several hundred modern personal computers (PCs).^[1] In this era mechanical analog computers were used for military applications.
Modern computers based on integrated circuits are millions to billions of times more capable than the early machines, and occupy a fraction of the space.^[2] Simple computers are small enough to fit into mobile devices, and mobile computers can be powered by small batteries. Personal computers in their various forms are icons of the Information Age and are what most people think of as “computers.” However, the embedded computers found in many devices from MP3 players to fighter aircraft and from toys to industrial robots are the most numerous.

History of computing

Etymology

The first recorded use of the word “computer” was in 1613 in a book called “The yong mans gleanings” by English writer Richard Braithwait I haue read the truest computer of Times, and the best Arithmetician that euer breathed, and he reduceth thy dayes into a short number. It referred to a person who carried out calculations, or computations, and the word continued with the same meaning until the middle of the 20th century. From the end of the 19th century the word began to take on its more familiar meaning, a machine that carries out computations.^[3]

Mechanical aids to computing

The history of the modern computer begins with two separate technologies, automated calculation and programmability. However no single device can be identified as the earliest computer, partly because of the inconsistent application of that term^[4]. A few precusors are worth mentioning though, like some mechanical aids to computing, which were very successful and survived for centuries until the advent of the electronic calculator, like the Sumerian abacus, designed around 2500 BC^[5] of which a descendant won a speed competition against a contemporary desk calculating machine in Japan in 1946,^[6] the slide rules, invented in the 1620s, which were carried on five Apollo space missions, including to the moon^[7] and arguably the astrolabe and the Antikythera mechanism, an ancient astronomical analog computer built by the Greeks around 80 BC.^[8] The Greek mathematician Hero of Alexandria (c. 10–70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions and when.^[9] This is the essence of programmability.

Mechanical calculators and programmable looms

Blaise Pascal invented the mechanical calculator in 1642,^[10] known as Pascal's calculator, it was the first machine to better human performance of arithmetical computations^[11] and would turn out to be the only functional mechanical calculator in the 17th century.^[12] Two hundred years later, in 1851, Thomas de Colmar released, after thirty years of development, his simplified arithmometer; it became the first machine to be commercialized because it was strong enough and reliable enough to be used daily in an office environment. The mechanical calculator was at the root of the development of computers in two separate ways. Initially, it was in trying to develop more powerful and more flexible calculators^[13] that the computer was first theorized by Charles Babbage^[14][15] and then developed.^[16] Secondly, development of a low-cost electronic calculator, successor to the mechanical calculator, resulted in the development by Intel^[17] of the first commercially available microprocessor integrated circuit.
In 1801, Joseph Marie Jacquard made an improvement to the textile loom by introducing a series of punched paper cards as a template which allowed his loom to weave intricate patterns automatically. The resulting Jacquard loom was an important step in the development of computers because the use of punched cards to define woven patterns can be viewed as an early, albeit limited, form of programmability.

First use of punched paper cards in computing

The Most Famous Image in the Early History of Computing^[18]

This portrait of Jacquard was woven in silk on a Jacquard loom and required 24,000 punched cards to create (1839). It was only produced to order. Charles Babbage started exhibiting this portrait in 1840 to explain how his analytical engine would work.^[19]

It was the fusion of automatic calculation with programmability that produced the first recognizable computers. In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer, his analytical engine.^[20] Limited finances and Babbage's inability to resist tinkering with the design meant that the device was never completed—nevertheless his son, Henry Babbage, completed a simplified version of the analytical engine's computing unit (the mill) in 1888. He gave a successful demonstration of its use in computing tables in 1906. This machine was given to the Science museum in South Kensington in 1910.

Ada Lovelace, considered to be the first computer programmer^[21]

Between 1842 and 1843, Ada Lovelace, an analyst of Charles Babbage's analytical engine, translated an article by Italian military engineer Luigi Menabrea on the engine, which she supplemented with an elaborate set of notes of her own. These notes contained what is considered the first computer program – that is, an algorithm encoded for processing by a machine. She also stated: “We may say most aptly, that the Analytical Engine weaves algebraical patterns just as the Jacquard-loom weaves flowers and leaves.”; furthermore she developed a vision on the capability of computers to go beyond mere calculating or number-crunching^[22] claiming that: should “...the fundamental relations of pitched sounds in the science of harmony and of musical composition...” be susceptible “...of adaptations to the action of the operating notation and mechanism of the engine...” it “...might compose elaborate and scientific pieces of music of any degree of complexity or extent”.^[23]
In the late 1880s, Herman Hollerith invented the recording of data on a machine-readable medium. Earlier uses of machine-readable media had been for control, not data. “After some initial trials with paper tape, he settled on punched cards...”^[24] To process these punched cards he invented the tabulator, and the keypunch machines. These three inventions were the foundation of the modern information processing industry. Large-scale automated data processing of punched cards was performed for the 1890 United States Census by Hollerith's company, which later became the core of IBM. By the end of the 19th century a number of ideas and technologies, that would later prove useful in the realization of practical computers, had begun to appear: Boolean algebra, the vacuum tube (thermionic valve), punched cards and tape, and the teleprinter.

First general-purpose computers

The Zuse Z3, 1941, considered the world's first working programmable, fully automatic computing machine.

During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers, which used a direct mechanical or electrical model of the problem as a basis for computation. However, these were not programmable and generally lacked the versatility and accuracy of modern digital computers.
Alan Turing is widely regarded as the father of modern computer science. In 1936, Turing provided an influential formalization of the concept of the algorithm and computation with the Turing machine, providing a blueprint for the electronic digital computer.^[25] Of his role in the creation of the modern computer, Time magazine in naming Turing one of the 100 most influential people of the 20th century, states: “The fact remains that everyone who taps at a keyboard, opening a spreadsheet or a word-processing program, is working on an incarnation of a Turing machine.”^[25]

The ENIAC, which became operational in 1946, is considered to be the first general-purpose electronic computer. Programmers Betty Jean Jennings (left) and Fran Bilas (right) are depicted here operating the ENIAC's main control panel.

EDSAC was one of the first computers to implement the stored-program (von Neumann) architecture.

The first really functional computer was the Z1, originally created by Germany's Konrad Zuse in his parents living room in 1936 to 1938, and it is considered to be the first electro-mechanical binary programmable (modern) computer.^[26]
George Stibitz is internationally recognized as a father of the modern digital computer. While working at Bell Labs in November 1937, Stibitz invented and built a relay-based calculator he dubbed the “Model K” (for “kitchen table,” on which he had assembled it), which was the first to use binary circuits to perform an arithmetic operation. Later models added greater sophistication including complex arithmetic and programmability.^[27]
The Atanasoff–Berry Computer (ABC) was the world's first electronic digital computer, albeit not programmable.^[28] Atanasoff is considered to be one of the fathers of the computer.^[29] Conceived in 1937 by Iowa State College physics professor John Atanasoff, and built with the assistance of graduate student Clifford Berry,^[30] the machine was not programmable, being designed only to solve systems of linear equations. The computer did employ parallel computation. A 1973 court ruling in a patent dispute found that the patent for the 1946 ENIAC computer derived from the Atanasoff–Berry Computer.
The first program-controlled computer was invented by Konrad Zuse, who built the Z3, an electromechanical computing machine, in 1941.^[31] The first programmable electronic computer was the Colossus, built in 1943 by Tommy Flowers.

Key steps towards modern computers

A succession of steadily more powerful and flexible computing devices were constructed in the 1930s and 1940s, gradually adding the key features that are seen in modern computers. The use of digital electronics (largely invented by Claude Shannon in 1937) and more flexible programmability were vitally important steps, but defining one point along this road as “the first digital electronic computer” is difficult.^{Shannon 1940} Notable achievements include:

• Konrad Zuse's electromechanical “Z machines.” The Z3 (1941) was the first working machine featuring binary arithmetic, including floating point arithmetic and a measure of programmability. In 1998 the Z3 was proved to be Turing complete, therefore being the world's first operational computer.^[32] Thus, Zuse is often regarded as the inventor of the computer.^{[33][34][35][36]}
• The non-programmable Atanasoff–Berry Computer (commenced in 1937, completed in 1941) which used vacuum tube based computation, binary numbers, and regenerative capacitor memory. The use of regenerative memory allowed it to be much more compact than its peers (being approximately the size of a large desk or workbench), since intermediate results could be stored and then fed back into the same set of computation elements.
• The secret British Colossus computers (1943),^[37] which had limited programmability but demonstrated that a device using thousands of tubes could be reasonably reliable and electronically re-programmable. It was used for breaking German wartime codes.
• The Harvard Mark I (1944), a large-scale electromechanical computer with limited programmability.^[38]
• The U.S. Army's Ballistic Research Laboratory ENIAC (1946), which used decimal arithmetic and is sometimes called the first general purpose electronic computer (since Konrad Zuse's Z3 of 1941 used electromagnets instead of electronics). Initially, however, ENIAC had an architecture which required rewiring a plugboard to change its programming.

Stored-program architecture

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Several developers of ENIAC, recognizing its flaws, came up with a far more flexible and elegant design, which came to be known as the “stored-program architecture” or von Neumann architecture. This design was first formally described by John von Neumann in the paper First Draft of a Report on the EDVAC, distributed in 1945. A number of projects to develop computers based on the stored-program architecture commenced around this time, the first of which was completed in 1948 at the University of Manchester in England, the Manchester Small-Scale Experimental Machine (SSEM or “Baby”). The Electronic Delay Storage Automatic Calculator (EDSAC), completed a year after the SSEM at Cambridge University, was the first practical, non-experimental implementation of the stored-program design and was put to use immediately for research work at the university. Shortly thereafter, the machine originally described by von Neumann's paper—EDVAC—was completed but did not see full-time use for an additional two years.
Nearly all modern computers implement some form of the stored-program architecture, making it the single trait by which the word “computer” is now defined. While the technologies used in computers have changed dramatically since the first electronic, general-purpose computers of the 1940s, most still use the von Neumann architecture.

Die of an Intel 80486DX2 microprocessor (actual size: 12×6.75 mm) in its packaging

Beginning in the 1950s, Soviet scientists Sergei Sobolev and Nikolay Brusentsov conducted research on ternary computers, devices that operated on a base three numbering system of -1, 0, and 1 rather than the conventional binary numbering system upon which most computers are based. They designed the Setun, a functional ternary computer, at Moscow State University. The device was put into limited production in the Soviet Union, but supplanted by the more common binary architecture.

Semiconductors and microprocessors

Computers using vacuum tubes as their electronic elements were in use throughout the 1950s, but by the 1960s they had been largely replaced by transistor-based machines, which were smaller, faster, cheaper to produce, required less power, and were more reliable. The first transistorized computer was demonstrated at the University of Manchester in 1953.^[39] In the 1970s, integrated circuit technology and the subsequent creation of microprocessors, such as the Intel 4004, further decreased size and cost and further increased speed and reliability of computers. By the late 1970s, many products such as video recorders contained dedicated computers called microcontrollers, and they started to appear as a replacement to mechanical controls in domestic appliances such as washing machines. The 1980s witnessed home computers and the now ubiquitous personal computer. With the evolution of the Internet, personal computers are becoming as common as the television and the telephone in the household.^{[citation needed]}
Modern smartphones are fully programmable computers in their own right, and as of 2009 may well be the most common form of such computers in existence.^{[citation needed]}

Programs

Alan Turing was an influential computer scientist.

The defining feature of modern computers which distinguishes them from all other machines is that they can be programmed. That is to say that some type of instructions (the program) can be given to the computer, and it will process them. Modern computers based on the von Neumann architecture often have machine code in the form of an imperative programming language.
In practical terms, a computer program may be just a few instructions or extend to many millions of instructions, as do the programs for word processors and web browsers for example. A typical modern computer can execute billions of instructions per second (gigaflops) and rarely makes a mistake over many years of operation. Large computer programs consisting of several million instructions may take teams of programmers years to write, and due to the complexity of the task almost certainly contain errors.

Stored program architecture

Main articles: Computer program and Computer programming

Replica of the Small-Scale Experimental Machine (SSEM), the world's first stored-program computer, at the Museum of Science and Industry in Manchester, England

This section applies to most common RAM machine-based computers.
In most cases, computer instructions are simple: add one number to another, move some data from one location to another, send a message to some external device, etc. These instructions are read from the computer's memory and are generally carried out (executed) in the order they were given. However, there are usually specialized instructions to tell the computer to jump ahead or backwards to some other place in the program and to carry on executing from there. These are called “jump” instructions (or branches). Furthermore, jump instructions may be made to happen conditionally so that different sequences of instructions may be used depending on the result of some previous calculation or some external event. Many computers directly support subroutines by providing a type of jump that “remembers” the location it jumped from and another instruction to return to the instruction following that jump instruction.
Program execution might be likened to reading a book. While a person will normally read each word and line in sequence, they may at times jump back to an earlier place in the text or skip sections that are not of interest. Similarly, a computer may sometimes go back and repeat the instructions in some section of the program over and over again until some internal condition is met. This is called the flow of control within the program and it is what allows the computer to perform tasks repeatedly without human intervention.
Comparatively, a person using a pocket calculator can perform a basic arithmetic operation such as adding two numbers with just a few button presses. But to add together all of the numbers from 1 to 1,000 would take thousands of button presses and a lot of time, with a near certainty of making a mistake. On the other hand, a computer may be programmed to do this with just a few simple instructions. For example:

      mov No. 0, sum     ; set sum to 0
      mov No. 1, num     ; set num to 1
loop: add num, sum    ; add num to sum
      add No. 1, num     ; add 1 to num
      cmp num, #1000  ; compare num to 1000
      ble loop        ; if num <= 1000, go back to 'loop'
      halt            ; end of program. stop running

Once told to run this program, the computer will perform the repetitive addition task without further human intervention. It will almost never make a mistake and a modern PC can complete the task in about a millionth of a second.^[40]

Bugs

Main article: Software bug

The actual first computer bug, a moth found trapped on a relay of the Harvard Mark II computer

Errors in computer programs are called “bugs.” They may be benign and not affect the usefulness of the program, or have only subtle effects. But in some cases, they may cause the program or the entire system to “hang,” becoming unresponsive to input such as mouse clicks or keystrokes, to completely fail, or to crash. Otherwise benign bugs may sometimes be harnessed for malicious intent by an unscrupulous user writing an exploit, code designed to take advantage of a bug and disrupt a computer's proper execution. Bugs are usually not the fault of the computer. Since computers merely execute the instructions they are given, bugs are nearly always the result of programmer error or an oversight made in the program's design.^[41]
Admiral Grace Hopper, an American computer scientist and developer of the first compiler, is credited for having first used the term “bugs” in computing after a dead moth was found shorting a relay in the Harvard Mark II computer in September 1947.^[42]

Machine code

In most computers, individual instructions are stored as machine code with each instruction being given a unique number (its operation code or opcode for short). The command to add two numbers together would have one opcode, the command to multiply them would have a different opcode and so on. The simplest computers are able to perform any of a handful of different instructions; the more complex computers have several hundred to choose from, each with a unique numerical code. Since the computer's memory is able to store numbers, it can also store the instruction codes. This leads to the important fact that entire programs (which are just lists of these instructions) can be represented as lists of numbers and can themselves be manipulated inside the computer in the same way as numeric data. The fundamental concept of storing programs in the computer's memory alongside the data they operate on is the crux of the von Neumann, or stored program, architecture. In some cases, a computer might store some or all of its program in memory that is kept separate from the data it operates on. This is called the Harvard architecture after the Harvard Mark I computer. Modern von Neumann computers display some traits of the Harvard architecture in their designs, such as in CPU caches.
While it is possible to write computer programs as long lists of numbers (machine language) and while this technique was used with many early computers,^[43] it is extremely tedious and potentially error-prone to do so in practice, especially for complicated programs. Instead, each basic instruction can be given a short name that is indicative of its function and easy to remember – a mnemonic such as ADD, SUB, MULT or JUMP. These mnemonics are collectively known as a computer's assembly language. Converting programs written in assembly language into something the computer can actually understand (machine language) is usually done by a computer program called an assembler.

A 1970s punched card containing one line from a FORTRAN program. The card reads: “Z(1) = Y + W(1)” and is labeled “PROJ039” for identification purposes.

Programming language

Main article: Programming language

Programming languages provide various ways of specifying programs for computers to run. Unlike natural languages, programming languages are designed to permit no ambiguity and to be concise. They are purely written languages and are often difficult to read aloud. They are generally either translated into machine code by a compiler or an assembler before being run, or translated directly at run time by an interpreter. Sometimes programs are executed by a hybrid method of the two techniques.

Low-level languages

Main article: Low-level programming language

Machine languages and the assembly languages that represent them (collectively termed low-level programming languages) tend to be unique to a particular type of computer. For instance, an ARM architecture computer (such as may be found in a PDA or a hand-held videogame) cannot understand the machine language of an Intel Pentium or the AMD Athlon 64 computer that might be in a PC.^[44]

Higher-level languages

Main article: High-level programming language

Though considerably easier than in machine language, writing long programs in assembly language is often difficult and is also error prone. Therefore, most practical programs are written in more abstract high-level programming languages that are able to express the needs of the programmer more conveniently (and thereby help reduce programmer error). High level languages are usually “compiled” into machine language (or sometimes into assembly language and then into machine language) using another computer program called a compiler.^[45] High level languages are less related to the workings of the target computer than assembly language, and more related to the language and structure of the problem(s) to be solved by the final program. It is therefore often possible to use different compilers to translate the same high level language program into the machine language of many different types of computer. This is part of the means by which software like video games may be made available for different computer architectures such as personal computers and various video game consoles.

Program design

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Program design of small programs is relatively simple and involves the analysis of the problem, collection of inputs, using the programming constructs within languages, devising or using established procedures and algorithms, providing data for output devices and solutions to the problem as applicable. As problems become larger and more complex, features such as subprograms, modules, formal documentation, and new paradigms such as object-oriented programming are encountered. Large programs involving thousands of line of code and more require formal software methodologies. The task of developing large software systems presents a significant intellectual challenge. Producing software with an acceptably high reliability within a predictable schedule and budget has historically been difficult; the academic and professional discipline of software engineering concentrates specifically on this challenge.

Components

Main articles: Central processing unit and Microprocessor

A general purpose computer has four main components: the arithmetic logic unit (ALU), the control unit, the memory, and the input and output devices (collectively termed I/O). These parts are interconnected by buses, often made of groups of wires.
Inside each of these parts are thousands to trillions of small electrical circuits which can be turned off or on by means of an electronic switch. Each circuit represents a bit (binary digit) of information so that when the circuit is on it represents a “1”, and when off it represents a “0” (in positive logic representation). The circuits are arranged in logic gates so that one or more of the circuits may control the state of one or more of the other circuits.
The control unit, ALU, registers, and basic I/O (and often other hardware closely linked with these) are collectively known as a central processing unit (CPU). Early CPUs were composed of many separate components but since the mid-1970s CPUs have typically been constructed on a single integrated circuit called a microprocessor.

Control unit

Main articles: CPU design and Control unit

Diagram showing how a particular MIPS architecture instruction would be decoded by the control system.

The control unit (often called a control system or central controller) manages the computer's various components; it reads and interprets (decodes) the program instructions, transforming them into a series of control signals which activate other parts of the computer.^[46] Control systems in advanced computers may change the order of some instructions so as to improve performance.
A key component common to all CPUs is the program counter, a special memory cell (a register) that keeps track of which location in memory the next instruction is to be read from.^[47]
The control system's function is as follows—note that this is a simplified description, and some of these steps may be performed concurrently or in a different order depending on the type of CPU:

1. Read the code for the next instruction from the cell indicated by the program counter.
2. Decode the numerical code for the instruction into a set of commands or signals for each of the other systems.
3. Increment the program counter so it points to the next instruction.
4. Read whatever data the instruction requires from cells in memory (or perhaps from an input device). The location of this required data is typically stored within the instruction code.
5. Provide the necessary data to an ALU or register.
6. If the instruction requires an ALU or specialized hardware to complete, instruct the hardware to perform the requested operation.
7. Write the result from the ALU back to a memory location or to a register or perhaps an output device.
8. Jump back to step (1).

Since the program counter is (conceptually) just another set of memory cells, it can be changed by calculations done in the ALU. Adding 100 to the program counter would cause the next instruction to be read from a place 100 locations further down the program. Instructions that modify the program counter are often known as “jumps” and allow for loops (instructions that are repeated by the computer) and often conditional instruction execution (both examples of control flow).
The sequence of operations that the control unit goes through to process an instruction is in itself like a short computer program, and indeed, in some more complex CPU designs, there is another yet smaller computer called a microsequencer, which runs a microcode program that causes all of these events to happen.

Arithmetic logic unit (ALU)

Main article: Arithmetic logic unit

The ALU is capable of performing two classes of operations: arithmetic and logic.^[48]
The set of arithmetic operations that a particular ALU supports may be limited to addition and subtraction, or might include multiplication, division, trigonometry functions such as sine, cosine, etc., and square roots. Some can only operate on whole numbers (integers) whilst others use floating point to represent real numbers, albeit with limited precision. However, any computer that is capable of performing just the simplest operations can be programmed to break down the more complex operations into simple steps that it can perform. Therefore, any computer can be programmed to perform any arithmetic operation—although it will take more time to do so if its ALU does not directly support the operation. An ALU may also compare numbers and return boolean truth values (true or false) depending on whether one is equal to, greater than or less than the other (“is 64 greater than 65?”).
Logic operations involve Boolean logic: AND, OR, XOR and NOT. These can be useful for creating complicated conditional statements and processing boolean logic.
Superscalar computers may contain multiple ALUs, allowing them to process several instructions simultaneously.^[49] Graphics processors and computers with SIMD and MIMD features often contain ALUs that can perform arithmetic on vectors and matrices.

Memory

Main article: Computer data storage

Magnetic core memory was the computer memory of choice throughout the 1960s, until it was replaced by semiconductor memory.

A computer's memory can be viewed as a list of cells into which numbers can be placed or read. Each cell has a numbered “address” and can store a single number. The computer can be instructed to “put the number 123 into the cell numbered 1357” or to “add the number that is in cell 1357 to the number that is in cell 2468 and put the answer into cell 1595.” The information stored in memory may represent practically anything. Letters, numbers, even computer instructions can be placed into memory with equal ease. Since the CPU does not differentiate between different types of information, it is the software's responsibility to give significance to what the memory sees as nothing but a series of numbers.
In almost all modern computers, each memory cell is set up to store binary numbers in groups of eight bits (called a byte). Each byte is able to represent 256 different numbers (2^8 = 256); either from 0 to 255 or −128 to +127. To store larger numbers, several consecutive bytes may be used (typically, two, four or eight). When negative numbers are required, they are usually stored in two's complement notation. Other arrangements are possible, but are usually not seen outside of specialized applications or historical contexts. A computer can store any kind of information in memory if it can be represented numerically. Modern computers have billions or even trillions of bytes of memory.
The CPU contains a special set of memory cells called registers that can be read and written to much more rapidly than the main memory area. There are typically between two and one hundred registers depending on the type of CPU. Registers are used for the most frequently needed data items to avoid having to access main memory every time data is needed. As data is constantly being worked on, reducing the need to access main memory (which is often slow compared to the ALU and control units) greatly increases the computer's speed.
Computer main memory comes in two principal varieties: random-access memory or RAM and read-only memory or ROM. RAM can be read and written to anytime the CPU commands it, but ROM is preloaded with data and software that never changes, therefore the CPU can only read from it. ROM is typically used to store the computer's initial start-up instructions. In general, the contents of RAM are erased when the power to the computer is turned off, but ROM retains its data indefinitely. In a PC, the ROM contains a specialized program called the BIOS that orchestrates loading the computer's operating system from the hard disk drive into RAM whenever the computer is turned on or reset. In embedded computers, which frequently do not have disk drives, all of the required software may be stored in ROM. Software stored in ROM is often called firmware, because it is notionally more like hardware than software. Flash memory blurs the distinction between ROM and RAM, as it retains its data when turned off but is also rewritable. It is typically much slower than conventional ROM and RAM however, so its use is restricted to applications where high speed is unnecessary.^[50]
In more sophisticated computers there may be one or more RAM cache memories, which are slower than registers but faster than main memory. Generally computers with this sort of cache are designed to move frequently needed data into the cache automatically, often without the need for any intervention on the programmer's part.

Input/output (I/O)

Main article: Input/output

Hard disk drives are common storage devices used with computers.

I/O is the means by which a computer exchanges information with the outside world.^[51] Devices that provide input or output to the computer are called peripherals.^[52] On a typical personal computer, peripherals include input devices like the keyboard and mouse, and output devices such as the display and printer. Hard disk drives, floppy disk drives and optical disc drives serve as both input and output devices. Computer networking is another form of I/O.
I/O devices are often complex computers in their own right, with their own CPU and memory. A graphics processing unit might contain fifty or more tiny computers that perform the calculations necessary to display 3D graphics.^{[citation needed]} Modern desktop computers contain many smaller computers that assist the main CPU in performing I/O.

Multitasking

Main article: Computer multitasking

While a computer may be viewed as running one gigantic program stored in its main memory, in some systems it is necessary to give the appearance of running several programs simultaneously. This is achieved by multitasking i.e. having the computer switch rapidly between running each program in turn.^[53]
One means by which this is done is with a special signal called an interrupt, which can periodically cause the computer to stop executing instructions where it was and do something else instead. By remembering where it was executing prior to the interrupt, the computer can return to that task later. If several programs are running “at the same time,” then the interrupt generator might be causing several hundred interrupts per second, causing a program switch each time. Since modern computers typically execute instructions several orders of magnitude faster than human perception, it may appear that many programs are running at the same time even though only one is ever executing in any given instant. This method of multitasking is sometimes termed “time-sharing” since each program is allocated a “slice” of time in turn.^[54]
Before the era of cheap computers, the principal use for multitasking was to allow many people to share the same computer.
Seemingly, multitasking would cause a computer that is switching between several programs to run more slowly, in direct proportion to the number of programs it is running, but most programs spend much of their time waiting for slow input/output devices to complete their tasks. If a program is waiting for the user to click on the mouse or press a key on the keyboard, then it will not take a “time slice” until the event it is waiting for has occurred. This frees up time for other programs to execute so that many programs may be run simultaneously without unacceptable speed loss.

Multiprocessing

Main article: Multiprocessing

Cray designed many supercomputers that used multiprocessing heavily.

Some computers are designed to distribute their work across several CPUs in a multiprocessing configuration, a technique once employed only in large and powerful machines such as supercomputers, mainframe computers and servers. Multiprocessor and multi-core (multiple CPUs on a single integrated circuit) personal and laptop computers are now widely available, and are being increasingly used in lower-end markets as a result.
Supercomputers in particular often have highly unique architectures that differ significantly from the basic stored-program architecture and from general purpose computers.^[55] They often feature thousands of CPUs, customized high-speed interconnects, and specialized computing hardware. Such designs tend to be useful only for specialized tasks due to the large scale of program organization required to successfully utilize most of the available resources at once. Supercomputers usually see usage in large-scale simulation, graphics rendering, and cryptography applications, as well as with other so-called “embarrassingly parallel” tasks.

Networking and the Internet

Main articles: Computer networking and Internet

Visualization of a portion of the routes on the Internet.

Computers have been used to coordinate information between multiple locations since the 1950s. The U.S. military's SAGE system was the first large-scale example of such a system, which led to a number of special-purpose commercial systems such as Sabre.^[56]
In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. The effort was funded by ARPA (now DARPA), and the computer network that resulted was called the ARPANET.^[57] The technologies that made the Arpanet possible spread and evolved.
In time, the network spread beyond academic and military institutions and became known as the Internet. The emergence of networking involved a redefinition of the nature and boundaries of the computer. Computer operating systems and applications were modified to include the ability to define and access the resources of other computers on the network, such as peripheral devices, stored information, and the like, as extensions of the resources of an individual computer. Initially these facilities were available primarily to people working in high-tech environments, but in the 1990s the spread of applications like e-mail and the World Wide Web, combined with the development of cheap, fast networking technologies like Ethernet and ADSL saw computer networking become almost ubiquitous. In fact, the number of computers that are networked is growing phenomenally. A very large proportion of personal computers regularly connect to the Internet to communicate and receive information. “Wireless” networking, often utilizing mobile phone networks, has meant networking is becoming increasingly ubiquitous even in mobile computing environments.

Computer architecture paradigms

There are many types of computer architectures:

• Quantum computer vs Chemical computer
• Scalar processor vs Vector processor
• Non-Uniform Memory Access (NUMA) computers
• Register machine vs Stack machine
• Harvard architecture vs von Neumann architecture
• Cellular architecture

The quantum computer architecture holds the most promise to revolutionize computing.^[58]
Logic gates are a common abstraction which can apply to most of the above digital or analog paradigms.
The ability to store and execute lists of instructions called programs makes computers extremely versatile, distinguishing them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a minimum capability (being Turing-complete) is, in principle, capable of performing the same tasks that any other computer can perform. Therefore any type of computer (netbook, supercomputer, cellular automaton, etc.) is able to perform the same computational tasks, given enough time and storage capacity.

Misconceptions

Main articles: Human computer and Harvard Computers

Women as computers in NACA High Speed Flight Station "Computer Room"

A computer does not need to be electronic, nor even have a processor, nor RAM, nor even a hard disk. While popular usage of the word “computer” is synonymous with a personal electronic computer, the modern^[59] definition of a computer is literally “A device that computes, especially a programmable [usually] electronic machine that performs high-speed mathematical or logical operations or that assembles, stores, correlates, or otherwise processes information.”^[60] Any device which processes information qualifies as a computer, especially if the processing is purposeful.

Required technology

Main article: Unconventional computing

Historically, computers evolved from mechanical computers and eventually from vacuum tubes to transistors. However, conceptually computational systems as flexible as a personal computer can be built out of almost anything. For example, a computer can be made out of billiard balls (billiard ball computer); an often quoted example.^{[citation needed]} More realistically, modern computers are made out of transistors made of photolithographed semiconductors.
There is active research to make computers out of many promising new types of technology, such as optical computers, DNA computers, neural computers, and quantum computers. Most computers are universal, and are able to calculate any computable function, and are limited only by their memory capacity and operating speed. However different designs of computers can give very different performance for particular problems; for example quantum computers can potentially break some modern encryption algorithms (by quantum factoring) very quickly.

Further topics

• Glossary of computers

Artificial intelligence

A computer will solve problems in exactly the way it is programmed to, without regard to efficiency, alternative solutions, possible shortcuts, or possible errors in the code. Computer programs that learn and adapt are part of the emerging field of artificial intelligence and machine learning.

Hardware

Main articles: Computer hardware and Personal computer hardware

The term hardware covers all of those parts of a computer that are tangible objects. Circuits, displays, power supplies, cables, keyboards, printers and mice are all hardware.

History of computing hardware

Main article: History of computing hardware

First generation (mechanical/electromechanical)	Calculators	Pascal's calculator, Arithmometer, Difference engine
	Programmable devices	Jacquard loom, Analytical engine, Harvard Mark I, Z3
Second generation (vacuum tubes)	Calculators	Atanasoff–Berry Computer, IBM 604, UNIVAC 60, UNIVAC 120
	Programmable devices	Colossus, ENIAC, Manchester Small-Scale Experimental Machine, EDSAC, Manchester Mark 1, Ferranti Pegasus, Ferranti Mercury, CSIRAC, EDVAC, UNIVAC I, IBM 701, IBM 702, IBM 650, Z22
Third generation (discrete transistors and SSI, MSI, LSI integrated circuits)	Mainframes	IBM 7090, IBM 7080, IBM System/360, BUNCH
	Minicomputer	PDP-8, PDP-11, IBM System/32, IBM System/36
Fourth generation (VLSI integrated circuits)	Minicomputer	VAX, IBM System i
	4-bit microcomputer	Intel 4004, Intel 4040
	8-bit microcomputer	Intel 8008, Intel 8080, Motorola 6800, Motorola 6809, MOS Technology 6502, Zilog Z80
	16-bit microcomputer	Intel 8088, Zilog Z8000, WDC 65816/65802
	32-bit microcomputer	Intel 80386, Pentium, Motorola 68000, ARM architecture
	64-bit microcomputer[61]	Alpha, MIPS, PA-RISC, PowerPC, SPARC, x86-64
	Embedded computer	Intel 8048, Intel 8051
	Personal computer	Desktop computer, Home computer, Laptop computer, Personal digital assistant (PDA), Portable computer, Tablet PC, Wearable computer
Theoretical/experimental	Quantum computer, Chemical computer, DNA computing, Optical computer, Spintronics based computer

Other hardware topics

Peripheral device (input/output)	Input	Mouse, keyboard, joystick, image scanner, webcam, graphics tablet, microphone
	Output	Monitor, printer, loudspeaker
	Both	Floppy disk drive, hard disk drive, optical disc drive, teleprinter
Computer busses	Short range	RS-232, SCSI, PCI, USB
	Long range (computer networking)	Ethernet, ATM, FDDI

Software

Main article: Computer software

Software refers to parts of the computer which do not have a material form, such as programs, data, protocols, etc. When software is stored in hardware that cannot easily be modified (such as BIOS ROM in an IBM PC compatible), it is sometimes called “firmware.”

Operating system	Unix and BSD	UNIX System V, IBM AIX, HP-UX, Solaris (SunOS), IRIX, List of BSD operating systems
	GNU/Linux	List of Linux distributions, Comparison of Linux distributions
	Microsoft Windows	Windows 95, Windows 98, Windows NT, Windows 2000, Windows Me, Windows XP, Windows Vista, Windows 7, Windows 8
	DOS	86-DOS (QDOS), IBM PC DOS, MS-DOS, DR-DOS, FreeDOS
	Mac OS	Mac OS classic, Mac OS X
	Embedded and real-time	List of embedded operating systems
	Experimental	Amoeba, Oberon/Bluebottle, Plan 9 from Bell Labs
Library	Multimedia	DirectX, OpenGL, OpenAL
	Programming library	C standard library, Standard Template Library
Data	Protocol	TCP/IP, Kermit, FTP, HTTP, SMTP
	File format	HTML, XML, JPEG, MPEG, PNG
User interface	Graphical user interface (WIMP)	Microsoft Windows, GNOME, KDE, QNX Photon, CDE, GEM, Aqua
	Text-based user interface	Command-line interface, Text user interface
Application	Office suite	Word processing, Desktop publishing, Presentation program, Database management system, Scheduling & Time management, Spreadsheet, Accounting software
	Internet Access	Browser, E-mail client, Web server, Mail transfer agent, Instant messaging
	Design and manufacturing	Computer-aided design, Computer-aided manufacturing, Plant management, Robotic manufacturing, Supply chain management
	Graphics	Raster graphics editor, Vector graphics editor, 3D modeler, Animation editor, 3D computer graphics, Video editing, Image processing
	Audio	Digital audio editor, Audio playback, Mixing, Audio synthesis, Computer music
	Software engineering	Compiler, Assembler, Interpreter, Debugger, Text editor, Integrated development environment, Software performance analysis, Revision control, Software configuration management
	Educational	Edutainment, Educational game, Serious game, Flight simulator
	Games	Strategy, Arcade, Puzzle, Simulation, First-person shooter, Platform, Massively multiplayer, Interactive fiction
	Misc	Artificial intelligence, Antivirus software, Malware scanner, Installer/Package management systems, File manager

Languages

There are thousands of different programming languages—some intended to be general purpose, others useful only for highly specialized applications.

Programming languages

Lists of programming languages	Timeline of programming languages, List of programming languages by category, Generational list of programming languages, List of programming languages, Non-English-based programming languages
Commonly used assembly languages	ARM, MIPS, x86
Commonly used high-level programming languages	Ada, BASIC, C, C++, C#, COBOL, Fortran, Java, Lisp, Pascal, Object Pascal
Commonly used scripting languages	Bourne script, JavaScript, Python, Ruby, PHP, Perl

Professions and organizations

As the use of computers has spread throughout society, there are an increasing number of careers involving computers.

Computer-related professions

Hardware-related	Electrical engineering, Electronic engineering, Computer engineering, Telecommunications engineering, Optical engineering, Nanoengineering
Software-related	Computer science, Computer engineering, Desktop publishing, Human–computer interaction, Information technology, Information systems, Computational science, Software engineering, Video game industry, Web design

The need for computers to work well together and to be able to exchange information has spawned the need for many standards organizations, clubs and societies of both a formal and informal nature.

Organizations

Standards groups	ANSI, IEC, IEEE, IETF, ISO, W3C
Professional societies	ACM, AIS, IET, IFIP, BCS
Free/open source software groups	Free Software Foundation, Mozilla Foundation, Apache Software Foundation